The aim of this work was to evaluate the roots influence on the shear strength of a clay soil and a sandy soil. Soil samples with and without roots were collected from experimental plantations of Atlantic Forest native species. The soil samples were then physically characterized and their shear strength tested in a laboratory. The results indicated that the soils’ shear strength and compressive strength were increased by the roots. In the sandy soil, roots influenced the shear strength by increasing the cohesion value (234%), while in the clay soil they influenced the shear strength mainly by increasing the cohesion value (32%) and the internal friction angle (14.4%). This information can ultimately be part of the technical justifications that ratify the use of plants in erosion control and slope stabilization works.
